Antionidants for mineral oil lubricants and compositions containing the same



Patented June 13, 19; 1

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momma son mu, o gg g gw COMPOSITIONS some Herschel G. Smith,Wallingford, and TroyL.

Centre Audubon, N. 3., ass

No Dre v ll, Lansdowne, Pa., and

ignore to Gulf Oil m Pittsburgh, Pa, a corporation of v John G. Peters,Co

a Application her 8, 1948,

Serial No. 84,238

This invention relates to antioxidants for mineral oil lubricants andcompositions containing the same, and more particularly, it relates toaddition agents for mineral oil lubricants which inhibit the oxidativedeterioration of said lubricants.

In the lubrication of internal combustion engines of all types,particularly when severe operating conditions are encountered, plainmineral lubricating oils often prove unsatisfactory in service becauseof the cxidative deterioration of the oil, with the attendant depositionon the engine surfaces of varnish, gum or sludge. Furthermore, manylubricating oil compositions which may be highly satisfactory for thelubrication of other mechanisms have been found wholly unsuitable foruse as turbine oils.

The formation of varnishes, gums and sludges on engine surfaces is dueat least in part to oxidation effects on mineral lubricating oils. Inturbine oils the problem of oxidation is further aggravated, because innormal use turbine oils rapidly become contaminated with water.

It is an object of this invention, therefore, to provide an additionagent for mineral oil lubricants which will inhibit the oxidativedeterioration of such lubricants.

It is a further object of this invention to provide improved mineral oillubricant compositions which are remarkably stable against oxidationunder service conditions.

These and other objects are accomplished by the present inventionwherein an addition agent for mineral oil lubricants is prepared bycondensing N-amylaniline, N-dimethylaniline and formaldehyde in thepresence of an activated clay catalyst, and recovering the condensationproduct. The condensation product so obtained is a, light-coloredproduct which, when addedto mineral oil lubricants, confers a remarkablystability against deterioration by oxidation. Such condensation productsand the mineral oil lubricant compositions containing them are believedto be novel and are considered parts of our invention. Contrary to whatmay be expected from the nature of the reactants, we do not obtainhighly condensed, insoluble resinous products. On the contrary, when theabove reactants are condensed in accordance with our invention, thereare obtained light-colored condensation products which are non-resinousand which are readily soluble in mineral oils.

In performing the condensation, the reactants are mixed and heated to amaximum temperature of 350 F. We have found that if the tempera- 5 from150 to 300' E.

The proportions of the reactants vary over a fairly wide range. For eachmol of N-amylaniline, there is employed from 1 to 4 mols of N-dimethylaniline and from 1 to 4 mols of formaldehyde. Ordinarily, it ispreferred to use from 5 to 10 per cent by weight of the activated claycatalyst, based on the total weight of the reactants. However, smalleramounts, as low as 1 per cent by weight, and larger amounts, as high as20 per cent by weight, may also be em-, ployed; but larger amounts thanabout 10 per cent by weight are ordinarily not necessary.

,In lieu of formaldehyde, and formaldehydeyielding compound, such asparaformaldehyde, dioxymethylene and trioxymethylene may be employed.-In such case, the amount of formaldehyde-yielding compound used isbased on the equivalentnumber of mols of formaldehyde yielded within therange of proportions of formaldehyde set iorth hereinabove. Accordingly,as used in the appended claims, the term formaldehyde" is intended toinclude formaldehydeyiiletlding compounds as well as formaldehyde itseVarious activated clay catalysts may be employed in accordance with ourinvention. Such materials are well known in the art and comprise anatural clay, such as bentonite, fullers earth floridin and smectite,which has been acid treated in order to activate the clay. Thesematerials are described in U. 8. Patent 1,898,165, for example.

In preparing our new addition agents, the reactants and catalyst areplaced into a reaction vessel which is then closed and the mixtureheated with agitation under reflux until all of the formaldehyde orformaldehyde-yielding compound has been consumed. At this time, thewater which is formed as a result of the condensation is removed,preferably under vacuum, and the dehydrated condensation product is thenfiltered to remove the activated clay catalyst. In some instances, it isdesirable to prepare our new addition agent in a concentrate in a,mineral lubricating oil which may then be diluted down with additionaloil to the concentration desired in the final lubricating composition.In such instances, the mineral lubricating oil may be added in a,suitable amount, say in a weight equal to the weight 0! reactants, tothe tion mix- 3 ture in the reaction vemel, and the condensation productobtained will then be a concentrated solution of the addition agent inthe mineral lubricating oil. v The condensation products obtained inaccordance with our invention are liquids or crystalline solids. Whilethe exact nature of the chemical composition of the condensationprodacts is unknown, all of the three reactants enter into a flnalunitary product. The exact manner in which the catalyst influences thereaction is unknown. However, regardless of any theory involved, the useof an activated clay catalyst is an essential feature of our invention,since if the catalyst is omitted, black, insoluble, resinouscondensation products are obtained.

The following examples illustrate the preparation of our new additionagent:

Example I.Into an iron vessel, there was introduced 1 pound molofN-amylaniline (183 pounds), 4 mols of N-dimethylaniline (484 pounds) and4 mols of formaldehyde, in 'a 37 per cent by weight aqueous solution(320 pounds).

Gravity, A. P. I 5.7 Color, N. P. A 2.5 Neutralization No 0.9

Example lI.--Example I was repeated using 1 mol of N-amylaniline, 3 molsof N-dimeth'ylaniline, 3 mols of formaldehyde and about 3 per cent byweight of an activated clay. The flltered prod uct had the followingproperties:

Gravity, A. P. I; 6.8 Color, N. P. A 2.5 NeutralizationNo 1.0

Example III.-Another antioxidant was prepared under theconditions-outlined in Example I using 1 mol of N-amylaniline, 3 mols oiN-dimethylaniline, 4 mols of formaldehyde and 15 percent by weight ofFiltrol (activated montmorillonite). The filtered product had thefollowing properties:

Gravity, A. P. I 4.0 Color, N. P. A 3.0 Neutralization No 1.8

The N-amylaniline used in the above examples was the normal amyl isomer.However any of the isomeric N-amylanilines may be used with goodresults.

The condensation products obtained in accordance with the abovedisclosure from N-amylaniline,N-dimethylanillne and formaldehyde in thepresence of an activated clay catalyst are excellent addition agents formineral oil lubricants. They are readily soluble in all types of mineraloils, that is paraflinic, naphthenic or mixed base mineral oils and canbe blended with mineral oils in high proportions to form' concentratedsolutions thereof, which may then be diluted down to the proportionsdesired in the final mineral oil lubricant composition. As stated, ournew addition agents are remarkably eflective in inhibiting the oxidativedeterioration of mineral oil lubricant compositions. For this purposesmall amounts of ournew addition agents are generally suflicient. Forexample, our addition agents may be added to mineral lubricating oils inminor amounts, say from 0.001 to l per cent by weight on the. mineraloil, sufficient to inhibit the oxidative deterioration of the oil.Largeramounts of our new addition agents may be used if desired but itis ordinarily unnecessary to do so.

The following examples illustrate the remarkable antioxidant effects ofour new addition agents. In the following examples, the base oil and thesame oil blended with our new addition agents .are subjected to astandard oxidation test which measures the stability of the oils tooxidation. The oxidation test referred to is a standard test designatedASTM D943-4'l T. Briefly, the test comprises subjecting the oil sampleto oxygen at a temperature of C. (203 1".) in the presence of water andan iron-copper catalyst. and determining the time required to build up aneutralization number of 2. The flow of oxygen is maintainedat 3 litersper hour. The remarkably efl 'ective stabilit to oxidation of mineraloil lubricant compositions containing our new addition agents isillustrated by the results shown in the following examples.

Example IV.--An improved steam iarrbine oil was prepared by treating aturbineoil base stock with 0.5 per cent' by weight of an additiveprepared according to Example I. A comparison of the properties of thebase oil and improved turbine 011 showed the following:

B proved 011 m on Gravi a 01m $52 ASTM Dora-411' m a, a L. as o a 4Organ e! fin:

ime xidized.Hrs I!) 4,210 Neutralization No 2. 0 2. 0

Example Ve-An improved motor-lubricating oil was prepared by treating ahighly refined motor lubricating oil base stock with 0.5 per cent byweight of the antioxidant prepared according The above examples show theremarkable oxidation stability imparted to mineral. oil lubricantcompositions by the use of our new addition agents. .Mineral oillubricant compositions containing our new addition agents are thereforeeminently suited for use where the operating conditions are extremelysevere, as in Diesel, tank and truck engines, and in the lubrication ofsteam turbines.

"I'he notable effects of our new addition agents cannot be readilyaccounted forand cannot be predicted from the nature of the reactants.Thus, condensation products prepared from other functionally similarcompounds have been found to be eitherprooxidant or to show noantioxidant effects whatsoever. For example, we have preparedcondensation products similar to our new addition-agents by substitutingxyli dine for sation products were found to be entirely unsuitable forinhibiting the oxidative deterioration of mineral oil lubricantcompositions.

While we have shown in the examples the preparation of compoundedlubricating oils, our invention is not limited thereto but comprises allmineral oil lubricant compositions containing our new addition agents,such as greases and the like. If desired, other known addition agentsmay be incorporated into the lubricant compositions prepared inaccordance with our invention. For example, pour point depressants.extreme-pressure agents, viscosity index improvers and the like may beadded.

Resort may be had to such modifications and variations as fall withinthe spirit of the inven tion and the scope of the appended claims.

We claim:

1. The process of preparing an addition agent for mineral oil lubricantswhich comprises heating 1 mol of N-amylaniline, 1 to 4 mols of N-dimethylaniline, and 1 to 4 mols of formaldehyde in the presence of anactivated clay catalyst at a temperature not in excess of 350 F. tocondense together the three reactants, and recovering the condensationproduct.

2. The process of preparing an addition agent for mineral oil lubricantswhich comprises heating 1 mol of N-amylaniline, 1 to 4 mols of N-dimethylaniline, and 1 to 4 mols of formaldehyde in the presence of anactivated clay catalyst at a temperature of from 150 to 300 F. tocondense together the three reactants, and recovering the condensationproduct.

3. The process of preparing an addition agent for mineral oil lubricantswhich comprises adding 1 mol of N-amylaniline, 1 to 4 mols ofN-dimethylaniline, 1 to 4 mols of formaldehyde and from 5 to 10 per centby weight on the foregoing reactants of an activated clay catalyst to amineral lubricating oil, heating the mixture at a temperature of from150 to 300 F. to condense together the three reactants, and recovering asolution of the condensation product in the mineral lubricating oil.

4. The process of preparing an addition agent for mineral oil lubricantswhich comprises heating 1 mol of N-amylaniline, 4 mols ofN-dimethylaniline and 4 mols of formaldehyde in the presence of 5 to 10per cent by weight of an activated clay catalyst at a temperature offrom 150 to 300 F. to condense together the three reactants, andrecovering the condensation prodnot.

5. The process of preparing an addition agent for mineral oil lubricantswhich comprises heating 1 mol of N-amylaniline, 3 mols ofN-dimethylaniline and 3 mols of formaldehyde in the presence of 5 to 10per cent by weight of an activated clay catalyst at a temperature offrom 150 to 300 F. to condense together the three reactants, andrecovering the condensation product.

6. The process of preparing an addition agent !or mineral oil lubricantswhich comprises heating 1 mol of N-amylaniline, 3 mols ofN-dimethylanillne and 4 mols of formaldehyde in the presence 5 to percent by weight of an activated clay catalyst at a temperature of from150 to 300 F. to condense together the three reactants, and recoveringthe condensation product. I

7. A non-resinous condensation product of 1 mol of N-amylaniline, 1 to 4mols of N-dimethylaniline and 1 is oi formaldehyde, said product beingobtained by the process of claim 1.

8. A non-resinous condensation product of 1 mol of N-amylaniline, 4 molsof N-dimethylaniline and 4 mols of formaldehyde, said product beingobtained by the process of claim 4.

9. A non-resinous condensation product of 1 mol of N-amylaniline, 3 molsof N-dimethylaniline and 3 mols of formaldehyde, said product beingobtained by the process of claim 5.

10. A non-resinous condensation product of 1 mole of N-amylaniline, 3mols of N -di methy1aniline and 4 mols of formaldehyde, said productbeing obtained by the process of claim 6.

11. A lubricant composition comprising a ma.- jor amount of a minerallubricating oil, and a minor amount, sufficient to inhibit the oxidativedeterioration of said oil of a non-resinous condensation product of 1mol of N-amylaniline, 1 to 4 mols of N-dimethylaniline and 1 to 4 mole,of formaldehyde, said product being obtained by the process of claim 1.

12. A lubricant composition comprising a major amount of a minerallubricating oil, and a minor amount, from 0.001 to 1.0 per cent byweight of said oil, of a non-resinous condensation product of 1 mol ofN-amylaniline, 1 m4 mols of N-dimethylaniline, and 1 to 4 mols of form'-aldehyde, said product being obtained by the process of claim 1.

13. A lubricant composition comprising a ma jor amount of a minerallubricating oil, and a minor amount, suflicientvto inhibit the oxidativedeterioration of said oil, of a non-resinous con- 4 mols of N-dimethylaniline, and 4 mols of formaldehyde, said product beingobtained by the.

process of claim 4.

14. The composition of claim 16, wherein said condensation product ispresent in an amount of 0.5 er cent by weight.

15. A lubricant composition comprising a major amount of a minerallubricating oil, and a minor amount, suflicient to inhibit the'oxidativedeterioration of said 011, of a non-resinous condensation product of 1mol of N-amylaniline, 3 mols of N-dimethylaniline and 3 mols offormaldehyde, said product being obtained by the process of claim 5.

16. A lubricant composition comprising a ma jor amount of a minerallubricating oil, and a minor amount, sufficient to inhibit the oxldatlvedeterioration of said oil, of a non-resinous condensation product of 1mol of N-amylaniline, 3 mols of N-dimethylaniline and 4 mols offormaldehyde, said product being obtained by the process of claim 6.

HERSCHEL G. SMITH. TROY L. CANTREI-IL JOHN G. PETERS.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,511,746June 13, 1950 HERSCHEL G. SMITH ET AL. It is hereby certified thaterrors appear in the printed specification of the above numbered patentrequiring correction as follows:

Column 1, line 40, for the Word remarkably read remarkable; column 2,line 18, for and read any; column 6, line 39, for the claimreferencenumeral 16 read 13 and that the said Letters Patent should beread With these corrections therein that the same may conform to therecord of the case in the Patent Ofiice.

Signed and sealed this 5th day of September, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommz'ssioner of Patents.

WWW

Certificate of Correction Patent No. 2,511,746 June 13, 1950 HERSCHEL G.SMITH ET AL. It is hereby certified that errors appear in the printedspecification of the above numbered patentrequiring correction asfollows:

Column 1, line 40, for the Word remarkably read remarkable; column 2,line 18, for and read any; column 6, line 39, for the claim referencenumeral 16 read 13;

and that the said Letters .Patent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Oflice.

Signed and sealed this 5th day of September, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gammz'ssz'oner of Patents.

12. A LUBRICANT COMPOSITION COMPARISING A MAJOR AMOUNT OF A MINERALLUBRICATING OIL, AND A MINOR AMOUNT, FROM 0.001 TO 1.0 PER CENT BYWEIGHT OF SAID OIL, OF A NON-RESINOUS CONDENSATION PRODUCT OF 1 MOL OFN-AMYLANILINE, 1 TO 4 MOLS ION OF N-DIMETHYLANILINE, AND 1 TO 4 MOLS OFFORMALDEHYDE, SAID PRODUCT BEING OBTAINED BY THE PROCESS OF CLAIM 1.